A conventional laser system includes a single laser medium, or rod, with its end surfaces coated with a special reflective substance that is responsive to the wavelength of light desired to be emitted from the system. Such a system is well adapted for generating a single wavelength of light, but is not readily amenable to modification for providing different wavelengths of light.
It is also known that laser mediums constructed with certain crystal solids, such as YAG and YLF type crystals or other liquid or gaseous substances, have the characteristic ability of emitting several distinct wavelengths of light. For example, the possible wavelengths of light generated by YAG type crystals are 1,064 and 1,320 nanometers (nm), and the possible wavelengths for YLF type crystals are 1,054 and 1,320 rim. In order to obtain the desired output of the crystal, that is, the desired wavelength, it is generally necessary to fix dielectric mirrors, having the proper reflectance properties, at the opposing ends of the laser crystal medium. This in turn means that a single, conventional laser cavity is relatively restricted as to the variety of wavelengths that it can generate, as the components are not conveniently replaceable with others.
Since many current applications of lasers are dependent on the wavelength of light produced by the system, and since some applications, particularly medical applications, may require the use of more than one wavelength during a single procedure or related procedures conducted in sequence, it is frequently necessary to utilize more than one type of laser system to carry out the overall procedure. This is particularly true with respect to the use of lasers in ophthalmic surgical procedures, where it is frequently necessary to use more than one type of laser, such as one for initial targeting purposes, and then another for the actual surgical operation. In view of the high cost of modern laser systems and the size and relatively cumbersome nature of such systems, there is clearly a need for an improved system that is capable of generating a variety of wavelengths, but yet remains relatively compact compared to the use of a plurality of separate systems. The present invention is directed to satisfying this need.